To optimize package imports in Next.js, you can use the following methods:
1. Use dynamic imports
Dynamic imports allow you to load modules only when they are needed. This can be useful for large packages that export many modules, or for modules that you only need on certain pages.
To use dynamic imports, you can use the import() function. For example, the following code will dynamically import the lodash module:
JavaScript
const lodash = await import('lodash');
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You can then use the lodash object as usual.
2. Use tree-shaking
Tree-shaking is a technique that removes unused code from your bundle. This can help to reduce the size of your bundle and improve performance.
To enable tree-shaking, you need to set the treeShaking option to true in your next.config.js file:
JavaScript
module.exports = {
treeShaking: true,
};
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3. Use the optimizePackageImports option
The optimizePackageImports option in next.config.js allows you to optimize the imports from certain packages. This can be useful for packages that export many modules, or for packages that use a barrel file.
To use the optimizePackageImports option, you need to add the package name(s) to the experimental.optimizePackageImports array in your next.config.js file. For example,
the following code will optimize the imports from the lodash and @mui/material packages:
JavaScript
module.exports = {
experimental: {
optimizePackageImports: ['lodash', '@mui/material'],
},
};
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4. Use a bundler plugin
There are a number of bundler plugins that can help you to optimize your package imports. For example, the @vercel/bundler-transform-optimize-imports plugin can optimize the imports from certain packages, similar to the optimizePackageImports option in next.config.js.
5. Use a module bundler
If you are using a module bundler such as Webpack or Rollup, you can use their built-in features to optimize your package imports. For example, Webpack has a built-in tree-shaking feature.
Which method should you use?
The best method for optimizing package imports in Next.js will depend on your specific needs. If you are using a large package that exports many modules, or if you only need certain modules on certain pages, then you should use dynamic imports. If you are concerned about the size of your bundle, then you should enable tree-shaking and use the optimizePackageImports option in next.config.js. If you are using a module bundler, then you can use their built-in features to optimize your package imports.
How we optimized package imports in Next.js at Vercel
At Vercel, we use a combination of the above methods to optimize package imports in Next.js. We use dynamic imports for large packages that export many modules, and for modules that we only need on certain pages. We also enable tree-shaking and use the optimizePackageImports option in next.config.js.
In addition, we have developed a bundler plugin called @vercel/bundler-transform-optimize-imports. This plugin optimizes the imports from certain packages, similar to the optimizePackageImports option in next.config.js.
By using these methods, we have been able to significantly reduce the size of our Next.js bundles, which has improved the performance of our applications.